1. Field of Invention
This invention relates to a process for producing polybenzimidazole products. More particularly, the invention relates to the production of thermoplastic polybenzimidazole shaped articles.
2. Prior Art
It is recognized that polybenzimidazoles in general and particularly aromatic polybenzimidazoles are characterized by a high degree of thermal stability. In the prior art, polybenzimidazole has been formed into fibers and membranes of wide utility which are highly resistant to heat degradation and chemical attacks.
Polybenzimidazole has also been formed into membranes useful in reverse osmosis or ultrafiltration processes. See, U.S. Pat. Nos. 3,699,038, 4,020,142, 4,385,148 and 4,512,894. A process for the production of polybenzimidazole semipermeable flat films and fibers is also dislosed in several patents. See, for example, U.S. Pat. Nos. 4,020,142 and 4,512,894.
However, in the prior art no process was disclosed for the production of molded polybenzimidazole shaped articles since the prior art polybenzimidazole polymers were intractable and thus incapable of being molded. Moreover, powders of prior art polybenzimidazoles, even when subjected to high temperature molding processes, would retain a powdered consistency and could therefore not be molded.
Also, in prior art processes for the production of polybenzimidazole, the polybenzimidazole is first dissolved in a solvent, such as N,N-dimethylacetamide. As an integral step in the final process for the production of the polybenzimidazole end product in these prior art processes, all or substantially all of that solvent used in the formation of the polybenzimidazole polymer dope was driven off prior to the formation of the desired polybenzimidazole product. Difficulties have often occurred in attempting to drive off this solvent.
It is therefore an object of this invention to provide a process for the production of useful polybenzimidazole products which retain significant amounts of the solvents used in the polybenzimidazole production process.
It is a further object of the invention to produce thermoplastic polybenzimidazole articles.
It is a still further object of the present invention to provide a process for the mixing of polybenzimidazole with assorted fillers and reinforcing aids such as fiber glass, titanium dioxide and graphite to produce fibers, films and shaped articles having enhanced strength properties.
These and other objects, as well as the scope, nature, and utilization of the invention will be apparent to those skilled in the art from the following detailed description and appended claims.